In modern traffic control systems there is an increasing demand to have automatic systems able to accomplish various tasks like speed check, access check (in particular city access authorization policy check), parking payment, toll payment and so on.
Most of the checks on vehicles are done manually by public officers or, in case of speed check and access check, with the aid of one or more cameras connected to a computer system that through an appropriate algorithm automatically recognizes the vehicle plates and checks the rules (e.g. the speed limit, authorization policy, etc.). Even the computerized systems always require a manual inspection since the reliability of the recognizing algorithms is limited.
From EP737603 there is known a method and apparatus for identification of stolen vehicles; the identification procedure involves equipping each vehicle with an electronic plate operating without an electrical supply (i.e. passive); the electronic plate may have information written on to it in a form which can be read by electromagnetic waves from a reading device; when irradiated, the electronic plate produces a signal containing the recorded information which may include the serial number; the serial number information may be locked in the electronic plate, but there may be further information which can be modified; this may include the registration number of the vehicle and the name of the insurance company; the information may be read by a pistol-shaped reading device which interrogates the electronic plate for the stored information.
From U.S. Pat. No. 5,083,200 there is known a method for identifying objects in motion, in particular vehicles, and systems for its implementation; the method includes several steps whenever the object is moving inside a predetermined identification zone following a predetermined movement axis; the steps are periodically acquiring images of the object in a predetermined field of view, checking the nature of the image background in the field of view to obtain background reference information in the absence of the object, and processing the images acquired in combination with the background reference information in order to extract therefrom a silhouette of the object having crossed the field of view; this method and the corresponding systems may be used, in particular, with highway toll booths and for any other application demanding an identification of vehicles.
From U.S. Pat. No. 5,319,962 there is known a device for the identification of vehicle and equipment features; the device for the identification of vehicle features essentially comprises an electronic memory circuit which is arranged fixed to the vehicle and which can be read by an external apparatus which is to be connected to the vehicle; the memory is integrated into or onto a segment of the contact element support of a diagnosis socket, which segment is detachable from the latter; a part of a film-chip film circuit can very advantageously be used for this purpose, as is known from the technology and production of electronic credit cards and data cards; the electronic memory is initially written at the factory during the production of the vehicle, and then reflects the original equipment features of the vehicle. In the event of an installation or modification for the special equipment of the vehicle, the contents of the memory can be modified or updated electrically by the apparatus.
Automatic toll systems for highways are also known (called in Italy “Telepass”) based on a radio receiver installed at a toll gate (mains powered) and radio transmitters installed on the vehicles (battery powered); by way of a dedicated radio communication protocol when a vehicle goes through the gate the vehicle identity is transferred from the transmitter to the receiver and a corresponding bill is sent to the vehicle's owner.